The socioeconomic status of white ethnics

In the post below on the prolific nature of the Kennedy clan some commenters were curious as to the general socioeconomic slant of Irish Catholics. The GSS has a variable ETHNIC which asks which nation an individual's ancestors came from. Combine that with RELIG, and you can figure out how Irish Catholics stack up nationally. While I was looking at Irish Catholics I thought I would look at whites from various nations. I decided to exclude Jews from the analysis because I think there's a big difference between Polish Catholics and Polish Jews socioeconomically and we'd lose information aggregating. Further, I constrained the sample to non-Hispanic whites. To look at socioeconomic index I focused on the SEI variable. Here's how SEI is calculated: